1. Field of the Invention
The present invention relates to a rubber composition, and more particularly, to a rubber composition improved in high-loss property and fracture property due to an asphaltene-containing softening agent blended thereinto in a specific amount.
2. Description of the Related Arts
Asphalt has heretofore been added to rubber compositions for various purposes. For example, European Patent Publication No. 708137 discloses that a tire free from black stains on the surface even after being left standing for a long period of time can be prepared by forming a tire tread from a rubber composition containing asphalt.
It has been known that the high-loss property and fracture property of a rubber composition can be improved by compounding asphalt with the rubber composition. However, since asphalt is viscous and tacky, it is adhered or stuck to a mixer or the like during a mixing process, thereby failing to mix the asphalt into a rubber composition in a prescribed amount. Even when asphalt can be blended into a rubber composition in a desired amount, the fracture property is occasionally not sufficiently exhibited because of an insufficient dispersion thereof in the rubber composition.